There's a docker image with some instructions on Wiki, shouldn't be too tricky to transfer over. If I end up making it work I'll do a PR for the project wiki for Synology install steps.
I spent about a month looking for detailed guides on how to add individual services to my Synology and just constantly being frustrated.
Then I found an extremely detailed but very opinionated guide on how to setup a suite of apps with docker compose and ssh because the author's were very much against the GUI and built in apps. It's been a much smoother and easier experience installing services since I no longer need to seek out half baked guides on someone who got it working good enough for them on their NAS.